我需要在树莓派上(使用最新的Raspbian系统)通过串口实现两个设备之间的通信。两个设备都使用CP2102控制器并连接到树莓派。
通常情况下,当我向串口A发送命令时,设备A会通过串口A回复并通过串口B发送数据。然后,我需要将这些数据重新翻译给设备B(串口C),并从串口C接收答案。
问题在于,串口A的回复出现在串口B上,而串口B的数据出现在串口A上。
我尝试过不同的语言和串行库,但结果都是一样的。因此问题是:为什么在使用树莓派时会发生这种情况?如何在树莓派上实现这个功能?
附注:两个设备都能正常工作。我的C#代码运行良好。我使用了System.IO.Ports.SerialPort类来实现它,它看起来像Pi4J和RXTX解决方案。
附注2:下面是我尝试在RPi上使用的一些代码:
Serial, C ++:(非常糟糕的代码片段)
终端:
pi@pi ~ $ ls -l /dev/serial/by-id
total 0
Silicon_Labs_CP2102_USB_to_UART_Bridge_Controller_0001-if00-port0 -> ../../ttyUSB2
pi@pi ~ $ ls -l /dev/serial/by-path
total 0
platform-bcm2708_usb-usb-0:1.2.1:1.0-port0 -> ../../ttyUSB1
platform-bcm2708_usb-usb-0:1.2.4:1.0-port0 -> ../../ttyUSB2
platform-bcm2708_usb-usb-0:1.3:1.0-port0 -> ../../ttyUSB0
通常情况下,当我向串口A发送命令时,设备A会通过串口A回复并通过串口B发送数据。然后,我需要将这些数据重新翻译给设备B(串口C),并从串口C接收答案。
问题在于,串口A的回复出现在串口B上,而串口B的数据出现在串口A上。
我尝试过不同的语言和串行库,但结果都是一样的。因此问题是:为什么在使用树莓派时会发生这种情况?如何在树莓派上实现这个功能?
附注:两个设备都能正常工作。我的C#代码运行良好。我使用了System.IO.Ports.SerialPort类来实现它,它看起来像Pi4J和RXTX解决方案。
附注2:下面是我尝试在RPi上使用的一些代码:
Serial, C ++:(非常糟糕的代码片段)
Serial port("/dev/ttyUSB2", 115200U);
Serial port1("/dev/ttyUSB1", 115200U);
port1.setTimeout(Timeout::max(), 250, 0, 250, 0);
port.setTimeout(Timeout::max(), 250, 0, 250, 0);
cout << "Is the serial port open?";
if (port1.isOpen()) {
cout << " Yes." << endl;
uint8_t data[2] = { 0xAA, 0x00 };
port1.write(data, 2);
data[1] = 0xFF;
sleep(1);
port1.write(data, 2);
while (port.available() < 7);
int av = port.available();
string ss;
port.read(ss, av);
for (int i = 0; i < av; i++){
cout << (uint)ss.at(i) << " ";
}
cout << "av: " + (uint)av << endl;
}
RXTX,Java:
public class Bridge_rxtx {
public static final int baudrate = 115200;
protected SerialPort spDevB_Data;
SerialReader devB_DataListener;
protected SerialPort spDevA_Data;
SerialReader DevA_DataListener;
protected SerialPort spDevA_Control;
SerialPortEventListener DevA_ControlListener;
public Bridge_rxtx(String comDevB_Data, String comDevA_Data, String comDevA_Control) {
try {
spDevB_Data = setupPort(comDevB_Data);
spDevA_Data = setupPort(comDevA_Data);
spDevA_Control = setupPort(comDevA_Control);
} catch (Exception ignored){
ignored.printStackTrace();
}
try {
devB_DataListener = new SerialReader(spDevB_Data.getInputStream(), spDevA_Data.getOutputStream(), "B-A");
DevA_DataListener = new SerialReader(spDevA_Data.getInputStream(), spDevB_Data.getOutputStream(), "A-B");
DevA_ControlListener = new SerialPortEventListener() {
@Override
public void serialEvent(SerialPortEvent spe) {
throw new UnsupportedOperationException("Not supported yet.");
}
};
spDevB_Data.notifyOnDataAvailable(true);
spDevA_Data.notifyOnDataAvailable(true);
spDevA_Control.notifyOnDataAvailable(true);
} catch (IOException ex) {
Logger.getLogger(Bridge_rxtx.class.getName()).log(Level.SEVERE, null, ex);
}
}
public void launchBridge(){
System.out.println("Starting...");
try {
spDevA_Control.getOutputStream().write(new byte[] {(byte)0xAA, (byte) 0x00}, 0, 2);
} catch (IOException ex) {
Logger.getLogger(Bridge_rxtx.class.getName()).log(Level.SEVERE, null, ex);
}
try {
Thread.sleep(200);
} catch (InterruptedException ex) {
Logger.getLogger(Bridge_rxtx.class.getName()).log(Level.SEVERE, null, ex);
}
try {
spDevA_Control.getOutputStream().write(new byte[] {(byte)0xAA, (byte) 0xFF}, 0, 2);
} catch (IOException ex) {
Logger.getLogger(Bridge_rxtx.class.getName()).log(Level.SEVERE, null, ex);
}
System.out.println("Started");
}
SerialPort setupPort(String portName) throws Exception {
SerialPort serialPort = null;
CommPortIdentifier portIdentifier = CommPortIdentifier.getPortIdentifier(portName);
if (portIdentifier.isCurrentlyOwned()) {
System.out.println("Error: Port is currently in use");
} else {
CommPort commPort = portIdentifier.open(this.getClass().getName(), 2000);
if (commPort instanceof SerialPort) {
serialPort = (SerialPort) commPort;
serialPort.setSerialPortParams(baudrate, SerialPort.DATABITS_8, SerialPort.STOPBITS_1, SerialPort.PARITY_NONE);
} else {
System.out.println("Error: Only serial ports are handled by this code.");
}
}
return serialPort;
}
public static void main(String[] args) {
Bridge_rxtx bridge = new Bridge_rxtx("/dev/ttyUSB0", "/dev/ttyUSB2", "/dev/ttyUSB1");
bridge.launchBridge();
}
}
Pi4J,Java:
public class Bridge {
public static Bridge instance;
public static final int baudrate = 115200;
protected Serial spDevB_Data;
SerialDataListener devB_DataListener;
protected Serial spDevA_Data;
SerialDataListener devA_DataListener;
protected Serial spDevA_Control;
SerialDataListener devA_ControlListener;
private Bridge() {
}
public Bridge(String comDevB_Data, String comDevA_Data, String comDevA_Control) {
instance = this;
devA_ControlListener = new SerialDataListener() {
//SerialDataEvent in Pi4J doesn't support binary
//data by default. I implemented this myself.
public void dataReceived(SerialDataEvent event) {
System.out.println(bytesToHex(toPrimitives(event.getBinaryData())));
}
};
devB_DataListener = new SerialDataListener() {
public void dataReceived(SerialDataEvent event) {
byte[] data = toPrimitives(event.getBinaryData());
instance.spDevA_Data.write(data);
System.out.println("B -> A: " + bytesToHex(data));
}
};
devA_DataListener = new SerialDataListener() {
public void dataReceived(SerialDataEvent event) {
byte[] data = toPrimitives(event.getBinaryData());
instance.spDevB_Data.write(data);
try {
Thread.sleep(15);
} catch (InterruptedException ex) {
Logger.getLogger(Bridge.class.getName()).log(Level.SEVERE, null, ex);
}
System.out.println("B <- A: " + bytesToHex(data));
}
};
spDevB_Data = SerialFactory.createInstance();
spDevB_Data.addListener(devB_DataListener);
spDevA_Data = SerialFactory.createInstance();
spDevA_Data.addListener(devA_ControlListener);
spDevA_Control = SerialFactory.createInstance();
spDevA_Control.addListener(devA_DataListener);
spDevB_Data.setMonitorInterval(40);
spDevA_Data.setMonitorInterval(80);
spDevA_Control.setMonitorInterval(25);
spDevB_Data.open(comDevB_Data, baudrate);
spDevA_Data.open(comDevA_Data, baudrate);
spDevA_Control.open(comDevA_Control, baudrate);
}
public void SetupBridge() {
spDevA_Control.write(new byte[]{(byte) 0xAA, (byte) 0x00});
try {
Thread.sleep(20);
} catch (InterruptedException ex) {
Logger.getLogger(Bridge.class.getName()).log(Level.SEVERE, null, ex);
}
spDevA_Control.write(new byte[]{(byte) 0xAA, (byte) 0xFF});
}
}